1. Field of the Invention
The present invention generally relates to an apparatus and method for forming wiring substrates and device substrates by using a jet unit that jets materials containing fine particles and performs pattern formation, a material used for the apparatus, and the wiring substrates and devices formed by the apparatus.
2. Description of the Related Art
In recent years, various elements of light emitting devices/media and light processing device/media using minute fine particles/ultra fine particles have been studied. In order to apply fine particles to various devices, high density integration obtained by depositing films or layers that include fine particle material on a solid substrate is important. Thin films being integrated with fine particles in high density are disclosed in, for example, Light Emitting Device (Alivisatos et al.), Photoelectric Transfer Device (Greenham, N. C., et al., Phys, Rev. B, 54, 17628 (1996)), Ultra High-Speed Detector (Bhargava), Electroluminescence Display and Panel (Bhargava, Alivisatos et al.), Nanostructure Memory Device (Chen et al.), Multicolor Device from Nano particle alignment (Dushkin et al.).
Meanwhile, as for methods for forming thin films of inorganic compounds with excellent orientation, there are, for example, a molecular beam epitaxy method (MBE), a cluster ion beam method, an ion beam irradiation vacuum deposition method, a chemical vapor deposition method (CVD), a physical vapor deposition method (PVD), and a liquid phase epitaxy method (LPE). As for a method of forming thin films of organic compounds, there is, for example, a Langmuir Blow jet method (LB method). Quantum particles may be obtained by allowing materials sublimed in high vacuum with a vacuum apparatus (e.g. MBE) to form particles on a solid substrate in a self-organized manner.
The foregoing methods, however, has difficulty in controlling space between particles or size distribution of particles, and requires large cost for obtaining a desired structure. Therefore, in order to solve such problems, liquid jet techniques, that is, techniques of forming a film of a material including fine particles by using liquid jet head are being proposed. For example, in Japanese Patent Laid-Open Application No. 2000-126681, an emulsion including nanoparticles is coated on a solid substrate by an inkjet coating technique, to thereby form a thin film formed of an ultra fine particle (nanoparticle) aggregate, in which the thin film provides a function of increasing or memorizing photoluminescence strength as a function of the time or amount of irradiation of excitation light.
Other than applying the liquid jet technique to functional devices, the liquid jet technique may also be employed for fabricating circuit boards. Some examples of conventional known methods for fabricating circuit boards are described below.    (1) A method of forming a copper wiring pattern in which the copper wiring pattern is formed where a copper-clad laminate is covered with resist, is then exposed to form a circuit pattern with a photolithographic method, is then dissolved for removing unexposed resist, and is then etched at its resist-removed portions.    (2) A method of forming a conductive pattern in which the conductive pattern is formed where a ceramic substrate is applied with a conductive paste for printing a desired circuit pattern by using a screen printing technique, and is then thermally processed in a nonoxide atmosphere for sintering metal fine particles in the conductive paste.    (3) A method of forming a copper wiring pattern in which the copper wiring pattern is formed where an insulating substrate, being formed with a thin conductive layer by deposition of conductive metal, is covered with resist, is then exposed to form a circuit pattern with a photolithographic method, is then dissolved for removing unexposed resist, and is then etched at its resist-removed portions.
Nevertheless, the foregoing conventional known methods are not suited for forming fine patterns. Therefore, a method of employing an ink jet technique (principle) is proposed. As an example of a method of forming wiring patterns and fabricating circuit boards by employing an ink jet technique, in Japanese Patent Laid-Open Application No.2002-134878, a circuit pattern is directly drawn onto a substrate with a metal paste. This method provides easy formation of fine patterns with a simple fabrication process, has no necessity of waste fluid disposal, and requires little manufacture cost.
Meanwhile, the inventor of the present invention also has disclosed a method of fabricating an electronic source substrate by employing an ink jet technique (principle) in Japanese Patent Laid Open Application No.2001-319567.
Although various proposals are made using the ink jet technique, applying the technique for forming various devices and substrate patterns is a new technology still having many undiscovered areas. In addition, unlike a case of applying ink to paper with an inkjet technique, there are still many problems to solve in a case of forming patterns on unabsorbent substrates.